The present invention relates to a device that is designed to prevent dental surgery instruments and accessories from dripping at the moment when they are switched off.
In the art field of dental surgery instruments and accessories, and of their hygiene and improvement in particular, attempts have been made to render operation more efficient and effective by adopting devices and/or systems that prevent handpieces from dripping at the moment when they are switched off. More exactly, a great number of power driven dental surgery instruments utilize a water spray for the purposes of cooling and flooding the treatment area. This is particularly true in the case of high speed drills, which incorporate a pair of air and water circuits that produce an atomized spray.
Where no such system is provided, water will tend to drip from the instrument immediately following switch-off, in an annoying and unacceptable manner. The drip-inhibiting devices currently incorporated into dental surgery equipment make use of a plenum connected to the air and water circuits of the spray facility.
Air pressure being greater than water pressure in the circuits in question, the plenum is connected with spring means designed to operate such that when a given instrument is switched on initially (effected automatically when the user lifts the instrument from its holder), the plenum charges, in readiness to perform its prescribed function at the moment when the instrument ceases operation.
More exactly, with the spring means no longer under pressure, the plenum is able to generate a degree of vacuum, and thus to draw back water occupying the circuit downstream of the plenum and in the branches to the various instrument handpieces. Conventionally, the plenum is located upstream of the entire set of instruments, so that the need arises for a unit of generous capacity, capable of handling pressure requirements for any and all of the instruments installed.
The use of a large capacity plenum is also dictated by the length of the downstream circuit, hence the considerable pressure losses that must be offset. Another reason for installing a large unit is that one must often anticipate the future use of new and/or different instruments with increased circuit capacities.
A first drawback with the single plenum system is that the smaller capacity, or shorter branches of the circuit will be subjected to an overabundant negative pressure, causing water to be drawn back a considerable distance from the handpiece outlet. Such a situation is totally unhygienic, inasmuch as water that may have become polluted in and around the handpiece outlet is drawn back too great a distance into the circuit, together with air which may also be polluted.
Knowing the rapidity with which germs are able to multiply in such an environment, and their ability to gain the internal parts of the main equipment circuit, it will be clear enough that hygiene is lacking in a system of this conventional type. Accordingly, the object of the present invention is to overcome the drawbacks described above.